Fine powder particles, typically less than about 15 micrometers in size, are used in a large number of different applications. Such particles may be made by a variety of techniques that produce homogeneous structures and chemical compositions within the particles. The particles are usually mixed into a flowable matrix or binder, which is then hardened by solidification or curing, so that the mixture may be used in structural applications. The resulting mixture exhibits properties of both phases. The properties of the mixture may be tailored through the compositions and relative amounts of the phases, the sizes of the particles, and other controllable parameters.
In an example discussed in U.S. Pat. Nos. 5,807,909 and 5,820,669, fine powder particles having compositions in the (Zn,MgCd)(AI,Ga)2O4 family are mixed with organic or inorganic binders to form white paints that are applied to the external surfaces of spacecraft such as communications satellites. The resulting paints have extremely low absorptances and high emissivities, and are therefore advantageously used on the sun-facing side of the spacecraft. They are also sufficiently electrically conductive to dissipate the electrostatic charges that otherwise build up on the external surfaces of the spacecraft during service and may disrupt the electronic systems of the spacecraft if not dissipated. The properties of the paints are retained and do not substantially degrade for many years in the high-radiation geosynchronous-orbit space environment.
While such paints have provided an important advance in the protection of spacecraft, there is always a need for further improvements. Additionally, because mixtures of particles in matrices and binders share some common characteristics regardless of their use, the sources of advancement in fields such as paints may yield beneficial results in other fields using such mixtures. The present invention fulfills the need for such improvements, and further provides related advantages.